Police in Livingston County say a woman told her 15-year-old granddaughter to take the girl's four-year-old sister on an errand with the family car.
They say the result was a rollover crash yesterday that left both girls injured.
Hamburg Township police say they're seeking to charge the grandmother with letting an unauthorized person drive.
Police say the woman sent the girls to a bank in Brighton.
They say the 15-year-old lost control of the car, and it struck a tree and rolled over about 35 miles west of Detroit.
The under-age driver received minor injuries, while the four-year-old broke her arm.